Digital language learning materials and systems developed based on the information technology are becoming increasingly popular and widespread around the world. With limited teaching resources and regional restrictions, a region-free self-study mode is very much desired by language learners. By eliminating the pronunciation learning obstacle and providing techniques for assessing, diagnosing, and correcting pronunciations, a region-free language learning mode can be created and learning a new language is made easy and convenient.
In order to resolve aforementioned problem, language learning systems have been developed to provide a self-study channel to language learners. In such a language learning system, audio files are recorded by inviting professionals to read specific language textbooks. When a language learner inputs a pronunciation into the language learning system according to a prearranged textbook, the language learning system compares the audio files recorded by the professionals and the pronunciation of the language learner and analyzes the difference to give a mark. In addition, in some language learning systems, some physical features of the pronunciation of the learner are detected, and feedback information is provided according to language learning theories. Moreover, in some other language learning systems, the pronunciation of the language learner is assessed by using the Gaussian model or the Gaussian mixture model according to certain physical features of the pronunciation or through a pronunciation verification technique. In aforementioned pronunciation assessment techniques, an overall weighted assessment, a single mark, or a simple comparison result is usually provided. Thus, the language learner cannot obtain adequate feedback information and the corresponding correction information. Thereby, such language learning systems are undesired by language learners and hinder the development of the industry.